The present invention relates generally to that class of machines having as their function the application of heat to the ground surface such as for agricultural purposes. Such equipment is wheel-supported for traversing a field thereby momentarily subjecting the ground surface to elevated temperatures to rid the ground of harmful bacterial and other organisms. Common practice by the growers of certain crops such as rye grass is the annual burning of the remaining field stubble after harvest. For many years open burning of the fields has been practiced, however public opposition to the resulting air pollution has resulted in legislation restricting and, in some instances, setting cut-off dates for such open field burning. Air pollution resulting from such burning can be severe depending on local atmospheric conditions.
In anticipation of a strict ban on open field burning, numerous efforts have been made to provide mobile field burners which ignite vegetation and, more importantly, subject the ground surface and soil to elevated temperatures adequate to kill objectionable bacteria which, if left, would jeopardize the following year's crop. Substantial problems in the development of field burning equipment have been encountered by reason of the following factors. For practical reasons the field burner must be of a size and speed to burn several acres per hour with the quantity of stubble per acre being such that severe temperatures are encountered by the burner structure. Further, to prevent escape of flames the burning must be completed during passage of the burner over the ground area being treated otherwise the open flame will ignite adjacent open field areas. Previous field burners have directly ignited the stubble with the burning completed prior to departure of the moving field burner away from the ignited stubble. Obviously the heat generated is substantial requiring most of the prior art structures to include non-metallic insulation which is susceptible to degradation by heat and shock loads, the latter caused by the uneven terrain over which the burners must travel. Sudden loads imparted to the heated burner structures can cause early structural failures. Still further the practicalities of field burning necessitated the prior apparatus being of substantial size which hindered their mobility from one burning site to another.